The present invention relates to aligning apparatus and more particularly to a method and apparatus for aligning spray nozzles in operations wherein liquid coolant is sprayed from nozzles onto a workpiece.
In a continuous casting operation liquid metal is poured from a hot metal ladle into a tundish and then fed into a water cooled continuous casting mold. The strand formed thereby is continuously withdrawn from the mold. As the hot metal contacts the walls of the water cooled mold a thin skin forms to surround the molten core of the strand. As the strand is withdrawn from the water cooled mold it enters a secondary cooling zone where it is supported between a plurality of withdrawal rolls and additional heat is withdrawn to further solidify the cast strand.
In order to develop secondary cooling practices for making a high quality product, consistent and controlled application of spray coolant is required. Most of the variation in coolant application has been eliminated by providing sophisticated equipment, i.e. computer set point control, feedback flow control loops, and automatic computer checking of spray nozzle plugging and erosion.
However, alignment of the spray nozzles, which strongly affects spray cooling efficiency, is often crudely accomplished introducing unpredictable variations in the strand temperature profile. For example, when a segment is removed for repair or replacement of rolls, the spray nozzle header pipes often must also be removed. Handling and movement of the headers invariably results in movement of the nozzles from prior alignment positions. Also, when nozzles are plugged or eroded, replacement or cleaning requires realignment.
Alignment is critical in a continuous strand casting machine having single wide angle nozzles because of the large tip to strand distance, e.g. 24 inches, the narrow spacing between the rolls, on the order of 1.5 to 3.0 inches, and the width of the strand, e.g. 76 inches. Any misalignment of the spray nozzle will result in the coolant impinging the rolls instead of the strand supported between the rolls. The spray must be centered directly between the rolls for direct impact on the strand to insure maximum efficiency. This is also true where other spray shapes are utilized, e.g. square or full cone sprays.
A method currently used to align the spray nozzles in the secondary cooling zone of a continuous casting machine involves adjusting the sprays after they are turned on until the spray appears to be passing the maximum amount of water between the rolls. This method has obvious drawbacks, not the least of which is the drenching of the mechanic when making adjustments to nozzles which are overhead. The certain probability of becoming wet causes the alignment procedure to be a disliked job, done carelessly or not at all, or put at the bottom of the maintenance work list, and frequently left undone because of insufficient time.